Ford_Assassin

iTrader: (4)

Hey guys, tossing a ZL1 blower on a LQ4 6.0 with a set of L92 heads along with a stock LS9 cam (going into a 2003 RCSB). I figure 1218's have got to be better than stock LS3 or LS9 springs.

Planning on 12 psi max boost (2.45" upper pulley, 10% overdrive crank pulley) in the 6000-6300 RPM range. Are 1218's enough for L92 valves being they are slightly heavier than hollow LS3 intake valves? I already have the springs from another project, never used. The next step for me would be a BTR .660" double spring kit, but if the 1218's will work, that saves me $230.

Thanks!!

JoeNova

Look into Howards LS springs. Similar to PAC1218s, but with slightly higher rates and they're much cheaper. Summit has them for $120-125.

KW Baraka

iTrader: (7)

I would do the PAC springs......they're proven!

That having been said......if it were MY car, it would get the PAC 1221 duel springs. These are a very durable spring.....plus, I just plain like dual springs better.

Best of luck whichever way you go!

KW

Ford_Assassin

iTrader: (4)

If I weren't using a stock cam, I would agree going with a set of doubles.

The PAC-1221 are pricey, I would go with BTR .660 kit.